I was using pip 1.0 on Ubuntu 12.04. The way I originally installed pip was by running sudo apt-get install python-pip. I wanted to upgrade, so I tried your solution. Afterwards, which pip did, in fact, output /usr/bin/pip, as expected, but running pip --version had an error ending with this: pkg_resources.DistributionNotFound: pip==1.5.5
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NickMay 9 '14 at 16:51